Cameras are rolling. The cast keeps growing. And politically plugged-in visitors who have scouted the New York-based set are purportedly loving every minute of it.

That’s the incredibly early read on “Alpha House,” the forthcoming Web series about the life and times of a group of Republican senators who reside together in a group house, as envisioned by “Doonesbury” creator Garry Trudeau.

The show, which is scheduled to debut on Amazon Prime sometime this November, follows the exploits of the titular roomies: John Goodman, playing embattled North Carolina Republican Gil John Biggs; Mark Consuelos, playing newly minted Sen. Andy Guzman; Matt Malloy, playing Sen. Louis Laffer; and Clark Johnson, playing Sen. Robert Bettencourt.

Alpha House Executive Producer Jonathan Alter told HOH they’re done shooting about a third of the first season (four episodes are in the can), and that Trudeau is busily shaping the satiric arc of the remaining installments.

“There are definitely going to be some things that strike people as familiar … but we’re not writing it from the headlines,” he said of the general tone of the show. And don’t expect a lot of stunt casting.

“It won’t be like ‘K Street,’” he asserted, citing HBO’s attempt to make stars of those inside the Beltway bubble.

The premise is that old guarders Goodman, Malloy and Johnson must wrestle with primary challenges from the far right, while Consuelos’ rock star freshman mulls a bid for the presidency.

“They were elected before the tea party and are now having to deal with the new reality,” Alter suggested of the tectonic shift plaguing the leads.

He said the show has gone to great lengths to faithfully re-create the look and feel of the congressional experience.

“We have re-created the Russell Office Building on a soundstage on Queens, N.Y.,” Alter said, adding that everything from the water fountains to the neglected mail chutes are carbon copies of the original.

Veteran Senate Democratic aide Jim Manley recently watched an “Alpha House” shoot and was, for the most part, impressed by the verisimilitude.

He noted, for instance, that the set designers had nailed the color scheme splayed across a fake Capitol hideaway — a shade of green that Manley described as “endemic to the place.”

Manley also offered some constructive criticism, urging show runners to post state flags and nameplates outside office doors, correcting a screwy seating arrangement in a faux briefing scene (“I told them staff would not be at the table,” he said.) and lobbying producers to dial down the fake staffers’ interaction with the stars.

“I didn’t think they were deferential enough,” Manley said of the eyebrow-raising dynamic.

And he couldn’t help but nitpick about the mock-up of the infamous group house, based on the home owned by Rep. George Miller, D-Calif., and shared with Sens. Richard J. Durbin, D-Ill., and Charles E. Schumer, D-N.Y. “I pointed out that it was awfully clean,” Manley quipped.